Electron discharge device



Oct. 6, 1936. D. JoURNEAUx ELECTRON DISCHARGE DEVICE Filed Sept. 30, 1932 xvii:

Patented Oct. 6, 1936 ELECTRON DISCHARGE DEKVICE Didier Journeaux, Wauwatosa, Wis., assigner to Allis-Chalmers Manufacturing Company, Milwaukee, Wis., a corporation of Delaware Application september so, 1932, serial No. 635,559 16 claims.l 01. 25a-27.5)

This invention relates to improvements in electron discharge devices, and more particularly to means for directing the flow of electronic current between the electrodes thereof. l

It is well known that, in electron discharge devices, the discharge path between two electrodes does not include the entire areas of the electrodes available for emitting or collecting electrons, but that such paths join the electrodes on comparatively small areas thereof. The flow of the clischarge causes a considerable amount of heat to be produced at the contact area between the discharge and the electrodes, thereby bringing such contact areas to high temperatures, thus tending to deteriorate the electrodes or to produce excessive amounts of metallic vapor and to evolve gases or vapors dissolved or occluded in the electrode material, hence tending to impair the operation of the devices. The location of the contact areas is determined by the relative position of the electrodes, by the path available for the discharge and by the presence of magnetic materials in the vicinity .of the discharge path. It has been proposed to insure a uniform distribution of the discharge over the entire electrode area by the use of electrostatic or electromagnetic means, but such means are only partially effective because of the extreme mobility of the discharge. By forcing the discharge to travel at a high velocity in the space adjacent the electrode, the point of attachment of the discharge will likewise travel over the electrode area, thereby insuring a uniform distribution 'of the heat generated over the entire electrode and avoiding the presence of hot spots thereon. Y

1t is, accordingly, one object of the present invention to provide an electron discharge device in which the point of attachment of the discharge to an electrode is forced to move during the entire discharge period.

Another object of the present invention isv toprovide an electron discharge device in which the point of attachment of the discharge to an electrode is moved continually over a closed circular path.

Another object of the present invention is to provide an electron discharge device in which the point of attachment of the discharge to an electrode is set in motion by magnetic means.

Another object of the present invention is to provide an electron discharge device in which- Fig. lis a vertical cross-sectional viewv of van,V

electron discharge device of the metallic vapor arcing type showing the electron emitting cathode and one of the anodes in cross-section;

Fig. 2 is a vertical cross-sectional view of a modified embodiment of one of the anodesV of the device;

Fig. 3 is a vertical cross-sectional View of a further modified embodiment of one` of the anodes of the device;

Fig. 4 is a horizontal cross-sectional view of the modifiedy embodiment shown in Fig. 3 and is taken on the plane IV-IV thereof.

Referring particularly to vthe drawing by characters yof reference, reference numeral II designates the casing of an electron discharge device shown as being of the metal enclosed type and as being provided with a water jacket for controlling the temperature in the device. The device is provided with a cathode generally represented by I2 and one or a plurality of anodes generally represented by I3. Each anode I3 comprises a portion extending through the casing or stem Ili and an arcing pprtionor head I6 assembled with portion I4 by suitable means such as a screw thread. Anode head I6 is formed Vin the shape of a hollow cylinder in which a helical slot is provided to permit such head to function as a solenoid. The lower or arcing surface of the anode head is made concave to prevent attachment of the arc to the central portion thereof where the magnetic field to be hereinafter described would be without effect in producing movement of such arc. The anode head may be made of any suitable conducting material such as iron or graphite, but is preferably made of non-magnetic material such as graphite or nickel-chromium-,ironI alloy. Anode I3 is supported through the casing in insulated relation by means of an insulato-r Il sealed to the casing and to the anode by suitable sealing means. Because of the difference in the coefficients of thermal expansion of the insulating material and of the metal, it is necessary that anode I3 be retained infinsulator I1 by a spring 20 to permit proper retention of the anode relative to the insulator at all temperatures. In particular, anode stern I4 is constantly maintained under tension, thereby insuring suitable mechanical and electrical contact of the screw threads of Yanode stem I4 and anode head I6. l A gasket I5 is interposed between anode' head VIIiand insulator Il to compensate for the unevenness of the surfaces thereof.

Each anode I3 is provided with an arc guide or housingv I8 which may be energized by suitable means (not shown) through a lead I9 eX- tending through' the casing of the .deviceas is, Well vknown in the art.. Eachanodemay also be provided with a control electrode 2| supported in housing I8 by means of insulators 22 and energized through a lead 23. The anode head is also surrounded by an electrostatic shield 24 which may be energized through a lead 26 extending through housing I8 in an insulator 21.

The cathode I2 is formed by a vaporizable metal such as mercury 36 constituting the active portion thereof, which is contained in a well formed by a metallic container or plate 31 and an insulator 38. The discharge is' confined to the central portion of the cathodeby a ring of insulating material 39 sealedl against the casing II of the device by a metallic ringv 4I. Plate j31 is provided with a Water jacket 42 for the purpose of controlling the temperature'thereof;

In operation, the discharge isinitiated andV maintained by any means known in the art and therefore not shown.` Upon positive energization of anode I3 with respect to cathode I2, current will flow through the several portions of anode I3, as shown in Fig. 3, by arrows, and will continue into. the space between anode I3 g and cathode I2 in the form of a discharge which is assumed to be concentrated on a portion of one edge of anode head I6 of Fig. 1 or 35 of Fig. 3. The flow of current in the solenoid portion of anode head I6 produces a magnetic eld 1ndicated, for example, in dotted arrows in Fig.

3. The lines of force of such magnetic field are substantially parallel inside of the anode head and diverge at the bottom part of such head to forml a iield having a radial component, and closethemselves in the space surrounding the anode head, some of the lines being carried, over part of their length, by any magnetic materials surrounding the anode head such as housing I8 or control electrode 2I. Some of the lines of force will close themselves through the coils of the solenoid, such tendency, however, being opposed by the space between the turns of the solenoid. If anode head I6 is made of non-magnetic material, the number oflines of force closing their paths through the solenoid will be considerably reduced, thereby leaving a larger number of lines of force present in the path of the discharge. As will appear from Fig. 3, the discharge crosses the lines of force and is, therefore, impelled in a direction which is tangential to the area of the lower part of the anode. The relative position of -the discharge end of the magnetic field being identical at any point of the anode surface, the discharge will continue to move in a circular path for the entire period of time during which the discharge is taking place. The velocity of the motion of the discharge is determined by the current intensity and by the intensity of the magnetic eld. It will be understood that, while in the absence of any magnetic field the discharge would produce heat only in the edge portion to which it is assumed `to be attached in Fig. 3, the production of heat is extended by the action of the magnetic field on the discharge to the entire lower area of the electrode'which, therefore, is at a substantially uniform temperature. Due to the resistanceV drop` and to the inductive dropin the coils of the solenoid,v the potential Aof anode 'head I6of Fig. 1 is higher at the upper part thereof than at the lower part so that the discharge therefrom may show a tendency to attach itself to the upper part of the anode head. Such attachment is prevented by the shield 24 which obstructs' the passage of the discharge to the upper part of the electrode. Such shield may be energized at a negative potential relative to cathode potential for repelling the electhrough`the Water being negligible compared to thatflowing .through the coils of solenoid 45. Flow of current through solenoid 45 causes the production of a radial magnetic eld similar to the field present in the anode shown in Fig. 3, thereby causing the point of attachment of the discharge to the liquid metal to travel with a circular motion. To obtain such result, plate 31 is made preferably of non-magnetic material such vas chromium-nickel alloy lthereby permitting extension of the lines of force over the surfaceY of liquid metalV 36. The travel of the discharge at the cathode does not eliminate the presence of an incandescent area at such point of attachment, but permits a rapid cooling of the area over which the point of attachment travels, thereby reducing the rate of vaporization of the metal.

In the embodiment shown in Fig. 2, anode head I6 is provided with an extension 28 for the purpose of adding to the anode a separate arcing portion 29 which is attached to extension 28 by suitable means such as screw threads. Arcing portion 29 is made of conductive material and is preferably made of non-magnetic material such as graphite or nickel-chromium-iron alloy to permit the extension of the lines of force produced by the flow of current in solenoid I6 into the space surrounding arcing portion 29. A set screw 3I may be provided for retaining arcing portion 29 in the proper relation on extension 28. Such portion 29 constitutes a short circuited secondary turn for solenoid I6 and will, therefore, receive eddy currents of considerable magnitude. Such eddy currents reduce the efliciency of the device and should, therefore, be reduced to the smallest possible value by suitable means such as slots 33 cut at intervals in portion 29 which increase the resistance to the ilow of eddy currents. The operation of the anode shown in Fig. 2 is similar to that of the anodes shown in Fig. 1 and need not be described further.

In the embodiment shown in Figs. 3 and 4, anode head I6 is formed as a spiral solenoid comprising at least two turns, the innermost turn 34 of the solenoid being of a lower height than the remaining turns 35'. The anode head no longer presents a continuous upper area suitable for engagement with insulator I1 and such engagement is, therefore, obtained by means of a circular disk piece 36 which receives gasket I5. In operation, upon energization of the anode, the discharge will attach itself to a portion of the outside turns 35 of the anode head because such turns are nearer the cathode than the innermost turn. The current will, therefore, ow from anode stem I4 through at least the innermost turn of the anode head and issue from the anode head in the form of a discharge. The current will thus circulate in at least y'one turn of the anode head and will produce a magnetic field as shown. Under the action of such magnetic eld, the discharge will travel in a circular path following the lower part of the anode head until its point of attachment reaches the end of the last turn of the anode head. Continued action of the magnetic field will cause the point of attachment of the discharge to jump the gap at the last turn of the anode head so that it will again travel over the last turn in a continuous motion for the whole length of time during which the discharge continues to take place.

Although but a few embodiments of the present invention have been illustrated and described, it will be apparent to those skilled in the art that Various changes and modifications may be made therein Without departing from the spirit of the invention or from the scope of the appended claims.

It is claimed and desired to secure by Letters Patent:

1. In an electron discharge device, an electron emitting electrode, an electron receiving electrode comprising a member formed to produce a magnetic eld thereabout as in a solenoid and a member conductively connected with and arranged about the field producing member to shield the surface thereof from electrons.

2. In an electron discharge device, an electron emitting electrode, and an electron receiving electrode With a portion of the surfaces thereof formed as a helix to produce a magnetic field about said electrode as in a solenoid and a shield arranged about the helical portion of said electron receiving electrode in spaced and insulated relation therewith to prevent the attachment of the electron discharge to the shielded portions thereof.

3. In an electron discharge device of the arcing type, a casing, an electron emitting electrode retained within said casing, an insulator extending into said casing, an electron receiving electrode extending through said insulator into said casing, the last said electrode being partially formed as a solenoid to produce a magnetic eld thereabout, and a shield arranged about the solenoid portion of the last said electrode to prevent access of electrons to such shielded portion from the first said electrode, said shield being supported by said insulator.

4. In an electron discharge device of the arcing type, a casing, an electron emitting electrode retained within said casing, a conductor connected with said electrode and extending through said casing, said conductor being formed as a solenoid to produce a magnetic field about said electrode, an insulator extending into said casing, an electron receiving electrode extending through said insulator into said casing, the last said electrode being partially formed as a solenoid to produce a magnetic eld thereabout, and a shield arranged about the solenoid portion of the last said electrode to prevent access of electrons to such shielded portion from the first said electrode, said shield being supported by said insulator.

5. In an electron discharge device, an electron emitting electrode, and an electron receiving electrode having a portion thereof formed substantially as a solenoid to produce a magnetic field thereabout and a portion secured to and substantially enclosing the solenoidal portion and arranged to receive electrons, the impingement of the electrons on the electron receiving portion being controlled by the magnetic eld of the solenoidal portion.

6. In an electron discharge device, an electron emitting electrode, an electron receiving electrode comprising a head portion having a portion thereof formed substantially as a helix and a portion closing the end of the helical portion, the helical portion producing a magnetic eld controlling impingement of electrons on the end closing portion, and a shield substantially enclosing only the helical portion of said electrode.

7. In an electron discharge device, an electron emitting electrode, an electron receiving electrode comprising a stem portion and a head portion having a portion thereof formed substantially as a helix and a portion closing the end of the helical portion, the helical portion producing a magnetic eld controlling impingement of electrons on the end closing portion, an insulator for insulating the stem portion from the device, and an electrostatic shield supported by said insulator and substantially enclosing only the helical portion of said electrode.

8. In an electron discharge device, an electron emitting electrode, and an electron receiving electrode having a portion thereof formed substantially as a solenoid to produce a magnetic field thereabout, and a portion secured to the solenoidal portion to receive electrons, the thickness of the electron receiving portion being less than the diameter of the solenoidal portion for' a predetermined number of ampere turns of the solenoidal portion so that a material portion of the magnetic field of the solenoidal portion closes itself outside of the electron receiving portion and in the path of the electron discharge to control the impingement of electrons thereon.

9. In an electron discharge device, an electron emitting electrode, and an electron receiving electrode having a portion thereof formed substantially as a solenoid to produce a magnetic field thereabout, and a non-magnetic portion se cured to the solenoidal portion to receive electrons, the thickness of the electron receiving portion being such relative to the diameter of the solenoidal portion that a material portion of the magnetic field extends outside of the electron receiving portion and in the path of the electron discharge to the electron receiving portion, whereby a control of the impingement of the electrons on the electron receiving portion is effected.

l0. In an electron discharge device, an electron emitting electrode, and an electron receiving electrode with electron receiving surfaces formed substantially as a flat spiral and comprising a plurality of turns Wound about each other, the inner turn being of relatively low height and the outer turn being of greater height than the inner turn and having the edge of its electron receiving surface extending beyond the edge of the inner turn toward said electron emitting electrode to cause the entire current fiowing between said electrodes to fiow through the inner turn to produce a magnetic field of material intensity about the outer turn for controlling the impingement of electrons thereon.

DIDIER JOURNEAUX. 

